1. Field of the Invention
The present invention relates to a material for finely isolated resist patterns capable of reducing an isolation size or hole size in the pattern when the resist pattern is formed in a semiconductor-manufacturing process, and to a method for forming a finely isolated pattern using the same. Further, The present invention relates to a method for manufacturing a semiconductor device using the finely isolated resist pattern, and to a semiconductor device manufactured according to the method.
2. Background Art
As semiconductor devices have been highly integrated, interconnections and isolation widths required in their manufacturing processes has become very fine. In general, a fine pattern is formed according to a method wherein a resist pattern is formed by a photolithographic technique, and various underlying thin films are respectively etched through the thus formed pattern as a mask.
For the formation of a fine pattern, the photolithographic technique is thus very important. The photolithographic technique includes resist coating, mask alignment, exposure to light, and development. This technique has a limit on the fineness due to the restriction imposed on the wavelength of the exposing light.
Further, the conventional lithographic process has a difficulty in controlling an etching resistance of a resist, making it impossible to fully control a surface profile so that the etched pattern is roughened on the surfaces of side walls by the control of the etching resistance.
As described above, when using the conventional photolithographic technique comprising light exposure, it has been difficult to form a fine resist pattern which exceeds the limit of the wavelength.
The present invention provides a water-soluble material which realize the formation of a finely isolated resist pattern for forming a fine isolation pattern or a fine hole pattern. The water-soluble material will ensures the formation of a fine pattern exceeding the wavelength limit, and will not dissolve an underlying resist. The present invention further provides a technique for forming a finely isolated resist pattern. The present invention also provides a technique of roughening the surfaces of side walls of a pattern after etching, which has been difficult in control according to the conventional lithographic technique.
Further, the present invention provides a method for manufacturing a semiconductor device by use of the technique of forming a finely isolated resist pattern, and also provides a semiconductor device manufactured by the method.
According to one aspect of the present invention, a fine pattern-forming material comprises one kind of water soluble resin, or a mixture of two or more kinds of water soluble resin, or a copolymer composed of two or more kinds of water soluble-resins as a main component, and which generates crosslinking reaction in the presence of an acid.
In another aspect of the present invention, in the fine pattern-forming material, said water soluble resin is comprised, as a main component, of polyacrylic acid, polyvinyl acetal, polyvinylpyrrolidone, polyvinyl alcohol, polethyleneimine, polyethylene oxide, styrene-maleic acid copolymer, polyvinylamine, polyallylamine, oxazoline group-containing resins, water-soluble melamine resins, water-soluble urea resins, alkyd resins, sulfone amide resins, or mixture thereof, or salt thereof.
According to one aspect of the present invention, a fine pattern-forming material comprises one or more kinds of water-soluble crosslinking agents as a main component, which generates crosslinking reaction in the presence of an acid.
In another aspect of the present invention, in the fine pattern-forming material, said water-soluble crosslinking agent is comprised, as a main component, of melamine, melamine derivative including alkoxymethylenemelamine, or urea derivative, benzoguanamine, glycoluril, or mixtures thereof.
In another aspect of the present invention, in the fine pattern-forming material, said urea derivative is comprised, as a main component, of urea, an alkoxymethyleneurea, N-alkoxymethyleneurea, ethyleneurea, ethyleneurea carboxylic acid, or mixtures thereof.
According to another aspect of the present invention, a fine pattern-forming material comprises, as a main component, a mixture of one or more kind of water-soluble resin and one or more kind of water-soluble crosslinking agent, which generates crosslinking reaction in the presence of an acid.
In another aspect of the present invention, in the fine pattern-forming material, said water-soluble resin is selected from polyvinyl acetal, polyvinyl alcohol, and a mixture of polyvinyl alcohol and polyvinyl acetal, and said water-soluble crosslinking agent is selected from a melamine derivative, a urea derivative, and a mixture of the melamine and urea derivatives.
According to another aspect of the present invention, in a method for manufacturing a semiconductor device, a first resist pattern is formed from a first resist on a semiconductor base layer. Said first resist pattern may or may not be subjected to a surface treatment by an acidic gas or heat treatment, light exposure, or both light exposure and heat treatment. On said first resist pattern, a second resist is formed which generates crosslinking reaction in the presence of an acid. A crosslinked film is formed at a portion of said second resist contacting with said first resist pattern by the agency of an acid fed from said first resist pattern. Non-crosslinked portions of said second resist is removed to form a second resist pattern. Finally, said semiconductor base layer is subjected to etching through the second resist pattern used as a mask.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said first resist comprises, as a main component, a mixture of novolac resin and a naphthoquinonediazide photosensitive agent.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said first resist is composed of a chemically amplified resist capable of generating an acid.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said second resist is composed of fine pattern-forming material as described above.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said second resist comprises fine pattern-forming material comprising, as a main component, a mixture of one or more water-soluble resins and one or more water-soluble cross-linking agents, wherein the water-soluble resin is selected from polyvinyl acetal, polyvinyl alcohol, and a mixture thereof, and the water-soluble cross-linking agent is selected from a melamine derivative, a urea derivative, and a mixture of the melamine and urea derivatives, and the degree of reaction with said first resist is controlled by controlling a mixing ratio between said water-soluble resin and said water-soluble crosslinking agent.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said second resist comprises polyvinyl acetal, and the degree of reaction with said first resist is controlled by controlling the degree of acetalization of said polyvinyl acetal.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, a solvent for said second resist is water or a water-soluble mixed solvent.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said first resist pattern and said second resist formed on said first resist pattern are thermally treated to form said crosslinked film in said second resist in contact with the surface of said first resist pattern.
In another aspect of the present invention, in the method for manufacturing a semiconductor device, said first resist pattern is subjected to irradiation with an electron beam at portions other than a predetermined region thereof, and said second resist is formed on the irradiated first resist pattern, and said crosslinked film is formed in the second resist on the predetermined region of said first resist pattern.
Other and further objects, features and advantages of the invention will appear more fully from the following description.